Molecular phylogeny of some European heteronemertean (Nemertea) species and the monophyletic status of Riseriellus, Lineus, and Micrura

The 16S rRNA mitochondrial gene was used to reconstruct the relationships among 10 heteronemertean species (subclass Heteronemertea, phylum Nemertea); Lineus ruber and L. viridis are represented by more than one specimen to assess intraspecific variation in these enigmatic species, and the analysis includes in total 14 terminal taxa incorporating one palaeonemertean species (Tubulanus annulatus) for outgroup rooting. The aligned sequences were subjected to maximum parsimony, maximum-likelihood, and neighbor-joining analyses to estimate the phylogenetic relationship of the species. The results were concordant from all analyses and indicate that neither Lineus nor Micrura are monophyletic taxa, and that there is no support from a phylogenetic point of view to establish the monotypic genus Riseriellus.